ISC-11 // Satellite Operations

GEO Sun-Outage / Eclipse Season Calculator

Predicts eclipse (Earth-shadow) seasons for geostationary satellites and the daily sun-transit outage window each satellite experiences around local midnight. Covers the full Indonesian GEO fleet — edit the list below to add, remove, or correct orbital slots.

Live fleet status —

Fleet configuration

Satellite	Operator	Slot (°E)	NORAD ID	Active

Eclipse duration and season dates are the same for every GEO satellite regardless of longitude — only the local time of day differs. Slot (°E) is used purely to convert eclipse timing into each satellite's local solar midnight. NORAD ID is shared with the Live Satellite Tracker tool — this fleet list is the same one used there.

Eclipse seasons — Year

Fleet snapshot for a specific date

Date

Satellite	Slot	In eclipse?	Duration	Start (UTC)	Mid (UTC)	End (UTC)	Start (WIB)	Mid (WIB)	End (WIB)

Per-satellite daily schedule

Satellite

Date	Season	Duration	Start (UTC)	Mid (UTC)	End (UTC)	Start (WIB)	Mid (WIB)	End (WIB)

Model: satellite treated as equatorial GEO (0° inclination) with Earth's shadow approximated as a cylinder of radius equal to Earth's mean radius (penumbra ignored). Sun declination and the equation of time use standard low-precision solar-position approximations (accurate to within a few minutes) — sufficient for ops planning, not propellant-grade. Eclipse duration formula: Δt = (P / (π·R_GEO)) · √(R_E² − R_GEO²·sin²δ), where P is the sidereal day, valid while |δ| stays below Earth's angular radius from GEO (≈8.70°). WIB = UTC+7.